medical Definition of palmar interosseus
: any of three small muscles of the palmar surface of the hand each of which arises from, extends along, and inserts on the side of the second, fourth, or fifth finger facing the middle finger and which acts to adduct its finger toward the middle finger, flex its metacarpophalangeal joint, and extend its distal two phalanges — called also
interosseus palmaris, palmar interosseous muscle
